This invention relates to devices for controlling operation of a humidifier in a forced air heating system.
It is desirable, in controlling operation of a humidifier in a forced air heating system, to energize the humidifier only when the furnace blower is energized. Generally, such operation maximizes the desired addition of moisture to the circulating air and minimizes the development of mineral deposits and corrosive agents.
A known prior art device for accomplishing the stated desired operation comprises a combined humidistat and sail-switch, model H49X, made by Honeywell. When the device is utilized, the sail portion of the sail-switch is located in an opening of a duct through which the air is forcibly circulated. Movement of the sail by the circulating air places the humidistat switch in an operable mode to enable it to perform its function of operating the humidifier in response to the relative humidity of the circulating air as sensed by a humidity sensing means located in the same duct opening as the sail. The referenced device also includes a plug and cord arrangement which eliminates having to make electrical connections with the blower motor wiring, thus simplifying installation of the humidification system.
While such a combined humidistat and sail-switch provides the desired system operation, it requires proper installation of the sail associated with the sail-switch. Also, in some applications, the sail must be trimmed to fit into the duct, thus making the installation somewhat more difficult and time consuming.